A microphone is generally a device converting voice into an electrical signal. The microphone should have good electronic and acoustic performance, reliability, and operability. Recently, a demand for a smaller microphone has been increased. Accordingly, a microphone using a micro electro mechanical system (MEMS) technology has been developed.
The MEMS microphone is manufactured using a semiconductor batch process. The MEMS microphone has a tolerance to heat and humidity as compared to a conventional electric condenser microphone (ECM), and may be down-sized and be integrated with a signal processing circuit.
In addition, the MEMS microphone has excellent sensitivity and low performance deviation for each of the products as compared to the conventional ECM. Accordingly, the MEMS microphone has been applied to many application fields instead of the ECM.
The MEMS microphone is generally classified into a piezoelectric MEMS microphone and a capacitive MEMS microphone.
The piezoelectric MEMS microphone includes a vibrating film, and when the vibrating film is deformed by external sound pressure, the electrical signal is generated by a piezoelectric effect to allow the sound pressure to be measured.
The capacitive microphone includes a fixed film and a vibrating film, and when the sound pressure is externally applied to the vibrating film, a capacitance value is changed while an interval between the fixed film and the vibrating film is changed. The sound pressure is measured by an electrical signal generated at this time.
However, since the conventional microphone requires two films such as the vibrating film and the fixed film to configure a parallel capacitor form, a process step thereof is complex. In addition, since a dimple structure should be formed in the vibrating film or the fixed film to prevent a stiction, an additional process is required, which causes a problem that manufacturing costs are increased.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention, and therefore, it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.